1. Technical Field
This disclosure relates generally to a topical skin care composition, and more specifically to a topical skin care composition formulated to provide accelerated production of collagen proteins.
2. Description of the Related Art
Collagen is one of the long, fibrous structural proteins whose functions are quite different from those of globular proteins such as enzymes. Collagen is the main protein of connective tissue in animals and the most abundant protein in mammals, making up about 40% of the total. It is tough and inextensible, with great tensile strength, and is the main component of cartilage, ligaments and tendons, and the main protein component of bone and teeth. Along with soft keratin, it is responsible for skin strength and elasticity, and its degradation leads to wrinkles that accompany aging. Collagen strengthens blood vessels and plays a role in tissue development. Collagen is present in the cornea and lens of the eye in crystalline form. It is also used in cosmetic surgery and burn surgery.
Collagen occurs in many places throughout the body, and in many different forms, each form being known as a type. There are at least 12 different types of collagen, with Type I collagen being the most abundant. The basic triple-helix structure of Type I collagen is the prototype for most of the other collagen types.
The other types of collagen differ from Type I collagen in the length of their triple helix and the presence or absence of globular domains at their amino or carboxyl terminal ends. Type I collagen may be found in skin, tendons, and bone, and Types I-III are recognized as playing a vital role in skin development and formation.
Collagen itself is made up of a unique Amino Acid (AA) and Imino Acid (IA) composition with 33% of the total residues being glycine (Gly), 10% proline (Pro), 10% hydroxyproline (Hyp), and about 1% hydroxylysine (Hyl).
The basic structural unit of Type I, II, and III collagen is tropocollagen, which is cross-linked to from large fibers of collagenous tissues. Tropocollagen is made of three polypeptide chains called α chains, where each of the α chains is wound around the other to form a triple helix structure. Every third AA or IA in the α chain is a glycine (hence the value of 33% for the relative amount of glycine present in collagen).
Sixty percent of the a chains are made of either the sequence Gly-Pro-X or the sequence Gly-X-Hyp, where X may be any AA or IA. The remaining forty percent of the a chains are various sequences of AAs and IAs, with every third AA or IA being a glycine. The AAs and IAs that compose tropocollagen may be referred to as tropocollagen factors.
A subset of particular proline and lysine residues in the region where the triple-helix formation occurs are hydroxylated before assembly can take place. Three enzymes are required for proper hydroxylation: lysl hydroxylase, prolyl-4-hydroxylase, and prolyl-3-hydroxylase.
Lysl hydroxylase converts lysines in the sequence X-Lys-Gly to 5-hydroxylysine. Prolyl-4-hydroxylase converts prolines in the sequence X-Pro-Gly to 4-hydroxyproline. Prolyl-3-hydroxylase converts prolines in the sequence Hyp-Pro-Gly to 3-hydroxyproline. The above hydroxylation reactions require Fe2+, ascorbic acid (vitamin C), oxygen, and α-ketoglutarate in the chemical reaction that is described below in equation (1).AA or IA residue+ascorbic acid+O2+α-ketoglutarate→hydroxyl-AA or IA+succinate  (1)
Since the presence of new collagen proteins encourages the replication of skin cells, the topical application of tropocollagen factors has been used to treat skin conditions such as sun-burn, malasma, wrinkling, telangiectasias (spider-veins), and dilated pores.
However, as was explained above, in order to hydroxylate new collagen proteins in order to synthesize new Type I, II, and III collagen, the tropocollagen factors found in conventional topical products must react with the pre-existing ascorbic acid that is found in the body.
Embodiments of the invention address this and other disadvantages of the conventional art.